This content originally appeared on Go Make Things and was authored by Go Make Things
In JavaScript, a rest parameter is a function parameter that gets assigned an array with all of the arguments that are passed from that point on in a function.
You define a rest parameter by creating a parameter prefixed with .... Any arguments provided at or beyond the rest parameter on a function get combined into an array that’s assigned to the rest parameter’s name.
You can only have one rest parameter on a function. In the example below, ...moreArgs is a rest parameter.
function logStuff (arg1, arg2, ...moreArgs) {
// Logs arg1
console.log(arg1);
// Logs arg2
console.log(arg2);
// Logs an array of any other arguments you pass in after arg2
console.log(moreArgs);
}
// In this example...
// arg1 = 'chicken'
// arg2 = 'tuna'
// moreArgs = ['chips', 'cookie', 'soda', 'delicious']
logStuff('chicken', 'tuna', 'chips', 'cookie', 'soda', 'delicious');
In yesterday’s article on default function parameters, we looked at an add() function for adding numbers together.
/**
* Add two numbers together
* @param {Number} num1 The first number
* @param {Number} num2 The second number
* @return {Number} The sum of both numbers
*/
function add (num1, num2) {
return num1 + num2;
}
If you wanted to add two or more numbers together, you could use a rest parameter to capture all numbers passed in, regardless of how many there were.
Here’s our add() function rewritten with a rest parameter.
function add (...nums) {
// Set a starting total
let total = 0;
// Add each number to the total
for (let num of nums) {
total += num;
}
// Return to the total
return total;
}
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This content originally appeared on Go Make Things and was authored by Go Make Things
Go Make Things | Sciencx (2023-03-15T14:30:00+00:00) Rest parameters in vanilla JavaScript. Retrieved from https://www.scien.cx/2023/03/15/rest-parameters-in-vanilla-javascript/
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